One common treatment for erectile dysfunction includes the use of a penile implant device. One type of penile implant device, commonly known as a three-piece device, includes a pair of inflatable cylindrical prostheses that are implanted into the corpus cavernosae of the penis, which are connected to a fluid-filled reservoir through a pump and valve assembly. Such a pump and valve assembly is typically implanted into the scrotum of the patient, and the reservoir is implanted in the abdomen. Tubing is used to connect each penile prosthesis to the pump, and additional tubing is used to connect the pump to the reservoir. To activate the penile implant device, the patient would typically actuate the pump using one of a variety of methods that cause fluid to be transferred from the reservoir through the pump and into the prostheses. This results in the inflation of the prostheses and produces rigidity for a normal erection. Then, when the patient desires to deflate the prostheses, a valve assembly within the pump is actuated in a manner such that the fluid in the prostheses is released back into the reservoir. This deflation returns the penis to a flaccid state.
The reservoir used in these three-piece systems is usually in the form of a flexible bag or bladder that can expand and contract in volume with movement of fluid to and from the reservoir. One commonly used method for manufacturing these reservoirs is by a dip coating process. Dip coating consists of introducing a mandrel of a desired geometry into a self-leveling thermoplastic or thermosetting material (e.g., a silicone dispersion of a specific solids content and viscosity). Much like old-fashioned candle making, the mandrel is repeatedly dipped into the dispersion until a desired wall thickness is obtained for the part. A period of time (e.g., 15 to 20 minutes) can be required between successive dipping processes to allow the previous coat of material to set sufficiently before initiating the next successive dip cycle. In the case of a spherical reservoir, for example, 24 to 28 dip cycles may be required to obtain a suitable wall thickness.
After a desired wall thickness is achieved, the reservoir produced by the mandrel coating process may be subjected to additional processing steps, such as placement in an oven for a curing process, for example. Curing is a step that is typically used in a process of preparing a thermosetting (e.g., silicone) reservoir body of a penile implant device. In some cases, an oven curing process can take a significant amount of time, such as 6 to 8 hours. After the curing process is complete, the coated mandrel is removed from the oven and allowed to cool to room temperature. The cured reservoir is then manually removed from the mandrel to complete the process. The total time from start to finish for a dip coating process can be 24 hours or more, and can be very costly and labor intensive. In addition, the dip coating process can require a relatively large manufacturing area, particularly when many reservoirs are being manufactured simultaneously.
The materials used for making reservoirs by dip-coating processes can also be expensive and time consuming to prepare, which further increases the cost and timing of producing a dip-coated implantable reservoir. One example of a material that is sometimes used in these dip-coating processes is a silicone dispersion that is a two-part platinum cure dispersion dispersed in xylene to convert from a semi-solid to a self-leveling liquid state. Preparation of the dispersion before it can be used for a dip-coating process can take 24 hours or longer, including the time required for mixing and de-airing. For manufacturing efficiency, the batches of material are generally made in relatively large quantities, which are usually very expensive. The effective cost of the dispersion further increases in cases where a portion of the dispersion is unused and must be discarded after its predetermined usable life.
The production of dip-coated implantable reservoirs also can be relatively complicated due to the number of parts and bonds required to incorporate the reservoir into a device that can be used in a prosthesis device. As an example, four components are often used to produce a typical dip coated reservoir assembly. These components include a molded silicone shell adapter, a silicone stand pipe, a dip coated reservoir shell, and section of kink resistant tubing. In this reservoir assembly, each of the individual components is bonded to an adjacent component using a suitable adhesive, such as a medical grade silicone adhesive. Each time a bond is made, an air (ambient) cure is performed, which generally take at least thirty minutes or longer, and which is followed by an oven cure generally for sixty minutes or longer before proceeding to the next bonding operation, thereby resulting in a process that is relatively slow, and time consuming. Thus, it is desirable to produce reservoir assemblies by methods and materials that are less costly than the production of reservoir assemblies using the dip coating and bonding methods described above.